I found a tactic that seems especially effective on those large maps, especially if the player is new, and not so experienced, or if the player has a huge stronghold. If both, it's even better.
But it is most effective when done fast. Really fast.
1. The first phase usually is a two-prong attack.
The first prong is purely a diversionary attack. Usually, it's a couple Laser or Microwave Lynx, or perhaps some Scorpions with a Spider or two. If the player is new, they would probably panic, and send as many combat vehicles as possible.
If you're playing as Plymouth, skip the next few steps, and send a couple EMP missiles their way, followed by an army of Spiders.
Then, there's the second prong. This is what I call the fast-strike expeditionary force. It's usually two to four Thor's Hammer, or Railgun if you don't have the tech yet, Lynx supported by one or two EMP Lynx.
Their objective is to establish and hold a foothold in the enemy stronghold.
2. The second phase is a critical step. The second wave goes in, usually a couple Railgun or Thor's Hammer Panthers and a couple EMP Panthers, and perhaps a couple Acid Cloud Panthers if you're facing Plymouth. Gets rid of those pesky Spiders and Scorpions.
They would be escorting ConVecs, holding the following: Vehicle Factory, Command Center, Garage, and perhaps a Observatory and Meteor Defense if you're playing Plymouth, and that player just loves to abuse the EMP missiles.
I would recommend building this base close enough to the enemy base, but not too close. Ring it with the best Guard Posts you can offer. You can also use it to send in harassment strikes. Especially effective if you're playing Plymouth.
3. Now, the enemy should be quite panicked. You've probably smashed a good-sized hole into his defenses, which, if he has a huge base, probably thought of as almost impregnable.
From the base you established earlier, you can use that as a staging point for the final strike. For me, it's all Tigers. Couple Thor's Hammer Tigers, one or two EMP Tigers, and perhaps an Acid Cloud Tiger or two. I'd also recommend some Starflares if you want to strike quickly.
Of course, this is the most timing-critical step.
Send in the Starflares, with some cannon fodder. Probably some Scouts. Position them next to vital structures. Such as reactors, structure factories, vehicle factories, or perhaps a Command Center if you can get to it. If you can find a densely-packed area with an Advanced Lab, try your best to get it.
After they all detonate, the opponent would probably be quite panicked right now. He'd probably be struggling to power down structures and rerouting the tubes.
If you have enough Starflares remaining, go for the Universities, Agridomes, Nurseries, Medical Centers, and Residences. Watch your opponenent's morale, and population, go bye-bye.
Then comes the final strike. Send in all the remaining Tigers as your opponent is trying to compensate for all the lost power, morale, population, food, and buildings.
Should be easy sailing by now.
If done fast enough, you should have crushed your opponent. If you feel merciful, perhaps transfer your opponenet several ConVecs and vehicles to get him back on his feet.
